markus2

91 Mark VII stock with 355 gears and shift kit.

I blew my headgasket over two months ago-
I put in 24 lb injectors with no computer tune.
Lotsa flat spots-
rough idle.
at steady speeds it will kinda "hickup" as im cruising along from time to time-like a miss almost or a fuel issue.

So...
i got a new set of ford racing 19 lb injectors to put in because that is what the car is programmed for.
New:TPS-voltage is correct
New:egr and sensor
New: IAC
New: Map
new motorcraft plugs-gap is accurate
new plugs, cap and rotor.
all fluids are clean
new fuel pump and fuel filter
NO VACUME LEAKS
Fuel pressure is on the money
bumped up timing and tried running 93-no pinging

idle is not as choppy as it was with 24's..
...but with the 19's in...
..
its still got a slight roll to the idle.
still has flat spots


I DONT KNOW WHAT TO DO.
IT IS SPEED DENSITY-

I have read about people swapping out old O2 sensors-even when there are no codes- (i have no codes coming out either)
I have also read that people drill a small hole in throttle body blade-(but i dont know if that will help at all because when im driving there are flat spots.

im really really lost here

mjr46

how did you verify no vaccum leaks were present??

markus2

with a working guage.
if there were leaks on an active vac line-when tapped into it with a guage it should jump around correct-and be all over.
It was steady.

quickvic91

what kind of work was done to your motor after the H/G failure?
For what its worth,i have a lopo 5.0,and put 19's instead of stock 14lb'ers. Runs wierd(flat spots/hesitation) on the light to part throttle,but after that, it opens up. Definately keep the 19's in,how is your AIC sensor,or your engine coolant temp sensor?A bad coolant temp sensor will make your car run like crap. Check the voltage on the two sensors,maybe even compression test,especially after a head gasket failure.
These two sensors are relatively cheap,less than 20 bucks,so its not like your screwed if they are bad.

markus2

Bad phrasing-on my behalf.
When I said "i blew my head gasket" i did.
But it was due to a bolt that was missing.
So on the headgasket you could see the burning marks where I assume it slowly burned away-because it was not creating a secure gasket seal due to the lack of pressure because of the missing bolt.

So I had the heads checked out by machine shop and honed.
They were fine.
The shop is a reputable shop-i have 120 percent faith in them.

I then put in 24 lb injectors before putting manifold back on.(mistake-because cpu is set up for 19's stock)
Replaced water pump
Repaired all vac leaks.

Put new Idle air control valve and sensor.
-TPS new
-EGR valve and sensor new.

Car still ran horrible after doin above sensors and valves.
So i figured it was due to the 24 lb injectors.

So i purchased new set of 19's from ford racing.
And car still idles bad-less of a roll-but bad.
Like a steady hickup ever few secs.

Car will loose all acceleration power-as if lack of fuel....
it wont stall....
than it comes reving back to life as if all is fine.

During normal accelerations my car will bog out right from a dead start sometimes.
It never stalls. just acts as if it does-(trying to be as descriptive as possible here-i know i dont sound very mechanical, just trying to overkill with description)

Sometimes-upon Light/Normal acceleration too WOT my car will just not pull as hard as it should-and under WOT it will take a delayed 2-3 sec until it litterally STEPS UP and starts pulling like it should. It pulls-but not hard and than like a few sec. later you can feel it like start pulling as if it goes from 140 hp to 200 hp-
its NOT a gradual step up in power ....
its an immeadiate step up-just delayed like 2-3 sec.


I replaced my fuel filter and pump with a 190 a few months back.
This all started I feel after the head gasket bla bla bla replacement.
It aint been the same since.

Voltage is fine on the IAC and everything else I replaced.

Engine coolant temp sensor????
I dont know where that is located?

I changed my fan clutch that has a built in temp sensor-for when to engage based on engine temp-I THINK THATS HOW THAT WORKS.
That built in temp sensor in my fan clutch is not the engine coolant temp sensor you are talking about right?

quickvic91

should be coming out of the front of the lower intake,right by the distributor, it should be a T fitting where the heater core hose goes and right on that fitting is the sensor. Your air charge temp sensor should be in the #1(or #2) intake runner on the lower manifold. if it isnt there,it may be located in the air intake tube/filter box.
any strange noises? ticking?(valvetrain noise)knocking or pinging?
Where is your timing exactly?10 degrees is baseline,12 to 14 advanced is good,anything more than 14 IMO is too much.

Joel5.0

Does the highlight above means no codes are output?...... as in not even a code 11 = System Pass output?

markus2

Installed new 02 sensors.

Night and day.
Idle is 90 percent better.
still a slight "hickup" to it-but less of a more extreme "surge" like it had.
Also upon acceleration the flat spots are gone-no more delay in power.

When I said no codes-NO ERROR CODES is what i meant to say.
Yes code 11 spits out
.....along with .....i forget the number but in ref. to the removal of the air pump assembly

I am about to order an ACT Sensor and Coolant Temperature Sender and sensor because.....

...Even though there is great improvement in overall drivability-the idle is still rough. And still has that hickup in power band as I drive at a steady cruising highway speed.


I do not know what my timing is- but it pings unless i run 93- i have been running 93 since a ford tech adjusted the timing for me. He told me to try driving it with 89-it still pinged. So he said trying running the 93 octane; i did; and now no more pinging.
I figured the timing was fine- because there is no pining now-so i assume it is rather high.

I do here like a light steady ticking noise from the engine.

markus2

CAR ISSUES RETURNED AFTER A FEW DRIVE CYCLES WITH THE NEW O2 sensors-things got better, and than back to square one

Installed new ACT sensor and coolant temp sensor.



When i say "car runs rough" .... the following is a list of specifics:


Car idles at around 700 rpm-
it has a constant shudder to it-you can hear it almost hickup every 2-3 seconds. When this "hickup occurs" the idle drops and rises again 50-100 rpms.

Under very slight gas_when in drive on a hill for example- its not a smooth opening of the throttle like the first couple hundred rpms or so have a rough shudder and not smooth.

I DO NOT HAVE AN ADJUSTABLE FUEL PRESSURE REGULATOR-
fuel pressure was on the money when checked after install of 8 new injectors about a month ago.



*note-that when I go around a turn or go into a turn and try to give it WOT-it almost wants to die at first sometimes or will pull at say 60 percent-and than once the car is straigtened out again, a second or two later-its as if it steps up a notch to 100 percent pulling power.
VERY VERY WEIRD.




had a 190 fuel pump put in 6 months ago. with the correct sock on it for a lincoln mark vii-not a mustang.
I used to have the problem that when it got to 1/4 tank or less on hills-my car would have fuel starvation issues and want to die almost until the car levels out again.
I thought this issue was from having the wrong size sock-so i replaced the sock with the new pump assembly and I began having no issues driving under a 1/4 of a tank.
NOW THAT PROBLEM IS BACK AND I HAVE NO CLUE WHY-
it is as if.... the same issue prior to the new fuel pump is back.
the exact issue.
what gives?


thanks guys
__________________


91 LSC SE-black on black on black
CAI
Pulleys and Smog Pump Eliminator
Rebuilt Trans w/ Shift Kit
3.55's out back
KYB's all around
190 lph
FORD RACING #19s injectors

Derf00

Is your evap system venting correctly? I recently read an article where they were chasing a similar problem and it turned out the Evap system was plugging up thus starving the car either at idle, around corners (fuel sloshing into vent hole in tank) and at WOT where you end up with a vacuum in your tank that makes the pump work harder.... Try driving with the gas cap off for a drive cycle or two. Granted you may kick on a light for the cap but if everything gets better, check your evap system.

I'm not totally up to to 91 cars so I may be talkin out my **** on this one. The car that was in the article was a 2002 or a 2003 ford (OBDII)